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<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
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<body>
    
</body>
<script>
    //判断成绩甲等（>90）,乙等（>80）,丙等（>60）,
    //let cj = prompt();
   /* var cj = prompt('请输入你的成绩');
    switch(cj){
        case 90://将类型转换为数据类型
            console.log('甲等');
            break;
        case 80:
            console.log('乙等');
            break; 
        case 60:
            console.log('丙等');
            break;
        default:
            console.log(cj);
    }*/
   //循环：打印1~100，计算1~100的和
   let sum = 0;
   for(let i=1;i<=100;i++){
      sum +=i//sum=sum+i;
   }
</script>
</html>
